Stoker control



Feb. 20, 1951 H. G. MANSON ET AL STOKER CONTROL 6 Sheets-Sheet 1 FiledMay 10, 1948 INVENTOES mam/a. MANSON ROBERT P MNSEN FW5173M ATTORNEYSFeb. 20, 1951 H. G. MANSON ET AL s'roxiza CONTROL Filed May 10, 1948 6Sheets-Sheet 2 INVENTORS n .n m x w, Wm 0 1. m W

Feb. 20, 1951 H. ca. MANSON ET AL 2,542,324

STOKER CONTROL Filed May 10, 1948 I 6 Sheets-Sheet 3 "WE/ TOPS G. MANSONROBERT I. HANSEN ITTORNEY.

Feb. 20, 1951 H. G. MANSON ET AL 2,542,824

STOKER CONTROL Filed May 0, 1948 6 Sheets-Sheet 4 IN VENTOIPS HARRY G.MANSON ROBERT E HANSEN BY Twflmm' 6? 7w ATTORNEYS Feb. 20, 1951 G.MANSON ET AL STOKER CONTROL 6 SheetsSheet 5 Filed May 10, 1948 INVENTORSHARRY G.MAN$ON ROBERT P HANSEN A T TORNE Y5 1951 H. G. MANSON ET AL2,542,824

STOKER CONTROL Filed May 10, 1948 6 Sheets-Sheet 6 II IIflIIIIIIAJINVENTORS HARRY G. MANSON ROBERT F. HANSEN BY l7 TTORNEYS Patented Feb.20, 1951 .1 1

STOKER CONTROL Harry G. Manson and Robert P. Hansen, Princeton, Ind.,assignors to Hansen Manufacturing Company, Princeton, Ind., acorporation of Indiana Application May 1948, Serial No. 26,058

9 Claims. 1

This invention relates to time switches, and particularly to devices ofthis type especially adapted for use in controlling stokers and similarmechanisms.

Most automatic stoker controls include an overall controlling portionwhich selects between normal day-time stoker operation and night-timeoperation which is generally of a hold-fire nature.

Such controls also usually include, and ordinarily as an entirelyseparate mechanism, instrumentalities for effecting hold-fire operationof the stoker during the night period.

A hold-fire control of this type consists of means for intermittentlyenergizing the stoker drive motor so that the fire which the stoker isfeeding is maintained at some predetermined burning rate which preventsthe fire from going out during the nightand which may also, especiallyin severe weather, provide sufiicient heat units to maintain thebuilding being heated up to a certain temperature.

As mentioned before, stoker controls of this type generally include thetwo sections identified above and which are generally separatelyconstructed although often placed in a single frame to be sold as aunit.

The present invention has as its primary object the construction of astoker control arrangement which is truly unitary in character in thatit employs only a single driving motor.

Another object of this invention is to provide an improved time switchto be adapted for use in stoker controls and the like and which is veryconvenient to adjust at any time.

i It is also an object of this invention to provide a time switch havinga driven part which is engaged and disengaged from the driving motor inorder to make it selectively eiiective or ineffec:

A still further object is the provision of a stoker control device whichis connected with building thermostats and the like and which operatesover a 24-hour period to control a stoker through normal and hold-fireoperations.

These and other objects and advantages will become more apparent uponreference to the following description taken in connection with. the vaccompanying drawings in which:

Figure 1 is a front elevational view showing a control switchconstructed according to this invention;

Figure 2 is a View looking at the switch in the I Figure 3 is a verticalsection indicated by the lines 33 on Figures 1 and 2;

Figure 4 is a vertical section indicated by the lines 4-4 on Figures 1and 2;

Figure 5 is a plan section indicated by the lines 55 on Figures 1 and2;

Figure 6 is a plan section indicated by the lines 6--6 on Figures 1 and2;

Figure '7 is a sectional view indicated by the lines 'l'l on Figures 5and 6;

Figure 8 is a vertical section indicated by the lines 8-8 on Figures 1and 2;

Figure 9 is a view showing a portion of the device illustrated in Figure2 in another operative position; and v Figure 10 is a wiring diagramshowing how the switch of this invention could be connected in circuitwith a stoker motor and suitable thermostatic valve switch forcontrolling the operation" of a stoker.

Referring to the drawings, the device of this invention comprises aframe or box like enclosure l0, and formed thereon as at I2 is a dialinscribed with numerals for indicating the hour and whether it be a. m.or p. m. A pointer l4 sweeps ove the said dial and an adjusting knob [6may be provided for correcting the position of the pointer [4 should theindicating position thereof be incorrect.

Adjacent the stationary dial !2 are a pair of other similarly inscribeddials l8 and 20 which are rotatable and geared to the pointer M torotate in unison therewith. Associated with each of the dials l8 and 20is a pointer 22 adjustablyconnected therewith and adapted for normallyrotating with the said dials. These pointers are adjustable to indicatecertain times of the day at which the device eiiects controllingadjust-- ments in the stoker motor operating circuits.

Also mounted on the frame I0 is a hold-fire or cycling arrangement 24including a dial 26 over which is movable a pointer 28. The device 24,as will become apparent hereinafter, is the holdfire part of the stokercontrol and is operable for intermittently energizing the stoker drivemotor and for predetermined periods of time thereby to prevent the fedfire from going out during the night or during any other period that thebuilding being warmed would not have to be kept up to full temperature.

The drive arrangement for the pointer l4 an the dials I8 and 29 is bestillustrated in Figures 2 and 3. In these figures it will be seen thatthe frame It] mounts a synchronous electricdrive motor 30 which carriesa pinion 32. The

pinion 32 runs on a gear 34 which is mounted on a shaft with anotherpinion 36. The pinion 36 in turn drives through a gear 38 which ismounted on the same shaft as the pinion 40. The pinion 40 drives into agear 42 which is frictionally connected with the shaft 44 that supportsthe' adjusting knob. I6 referredto above.

Pinned" to. the shaft. 44 is aother drive gear 46 and meshing with thegear 46 is a gear 48 carried on the shaft 50 which drives the pointerI4. Also meshing with the gear 46 is a gear 52 which is the same size asthe gear 48 and whichi's connected with the dial 20. A gear, 54 of. the;same size as the gears 48 and 52 also. meshes. with. the gear 46 and isconnected fon-drivingthedial. L8,. The connections between the gears 52and 54 and their respective dials 20 and I8 is best illustrated inFigure 6 wherein it will be seen that each of the said gears has asleeve part. and on. the end of which is mounted the associated dial.

. The frictional connection. of the. gear 42. with the shaft 44 permitsthe simultaneous adjustment' of the. pointer I4 and the. dials I8. and,20 in order to correct for the position. thereof when the. clock. hasbeen stopped. due. to the power being shut off or for some.- otherreason. Normally the frictional connection between. the. gear 42 and theshaft 44 is effected by. the spring washerindicated. at 43.and-issufiicient for maintaining a driving connection. between thesaidgear and-shaft.-

Each of the pointers. 22 is. connected withits;

corresponding dial .I.8:-or 20 by means of a spring pressed clutch.portion. indicated at- 5.6; pointers are squared to fit oven the square.por tion. 58 ot the; shafts; 60. and: thus. normally effeet; a. drivingengagement; between the. shatts and the. dials. However; when. thepointers.- are adjusted. relative. to the dials by; pulling the.-pointers out against their loading springs: and

turning them; the said shafts rotate with the pointers.

Attached to the shafts 60;,tha-t are within the recess 62. for-med in;the. back wall of. the frame.

I 0; are.- a pair of camwheels 64 each of. which carries: a cam member6.6 adapted for engage-'- ment w-ith asnap actionswitch mechanismindicated at. 68;. This switch mechanism will be best seen in Figures 6and '7, and it will be apparcut that it comprises" a togglemechanisminclu ing:an arm having aroller H1 at the end thereof which. wilL. beinaleftward. position after the switch has been actuated by the cam. 66associatedwith the dial- I8.. and in. a rightward po sitionafter the;switchhasbeen actuated by the .3

tact 16. when the. roller. is. in. its rightward pop sition.

As. explained. above,. each. of the. cam. wheels- 64 can be adjusted.relative. to. its driving. disc and thereby accurately controlsthe timeof day when the. switch. mechanism. 68. will. be. actuated by the camscarried. by the said. cam. wheels. Thus, over. a. period of Z-ihours.the. switch; mechanism. at168 will first be actuated. into. one positionbyone of the cam wheelsiand. theninto. another po sition. by the. other.of. the. cam wheels- The aforementioned. switch arrangement is for. thepurpose. of. selecting between daytime and night time operation. of the.stoken. During the. day time, as. will be. seen hereinafter, the.control of the stoker is effected by a thermostatic switch located inthe building being heated. During night time operation the operation ofthe stoker is controlled by a hold-fire mechanism which intermittentlyenergizes the stoker motor for predetermined periods of time.

Thehold-fire portion. of. thestoker control of this" invent-ion is-.bestseen in Figures 2, 4 and 9. This part of the stoker control comprises aframe oirbracket I8 which is mounted for free swinging movement about a.shaft extending through thebackwall of the frame or housing I0.

Mounted. in. the bracket I8 is a gear train comprising, a, gear 82pinned to the shaft 80, a

pinion. 84; meshingv with the gear 82 and a gear 85 rigidly mounted.with the pinion 84. The shaft. 89 also has mounted thereon an arm 88 andpositioned in the rotative path of the arm 8 8.ar.e: apair of spacedstops 90 and 92 carried by the bracket 18.

The. stop. $10. is angularly adjustablerelativeto the. bracket I8 bymeans of a. knob 94. which is.

rigidly connected with the stop an and which. may provide support forthe inner end of theshaft 80 as at 96..

A spring. washer. 98 provides frictional engagement between the. stopmember 90 and the bracket 18. so that when the said stop. member ispositioned by. turning the knob 94,. it will thereafter remain in thatposition. relative to. the bracket 1.8 until again. moved by the saidknob.

Reference to Figures. 2. and 9v will reveal that.

extending downwardl from. the. bottom of the bracket. 1.8, is and Hill.which extends through a. slot IE2 and a. plate. I04 pivoted. on a screwI06. Aspiring, IBBbears betweenthe plate I02 and: the bottom. of. the.bracket. 1.6, and provides. for. a. tog.-

gle. actionof the. bracket as itv moves about'theshaft 8I!, thus.snapping it. sharply into its two operative positions.

The extreme positions to which. the bracket 53 will move. are determinedby the slot I02 in plate I 04. and the stops III) positioned, one oneach. side of plate I04 and predetermining the .limits of movementthereof.

When the bracket I8 is in itslligure 2:position, the gear 85. mesheswith an idler pinion II2 mounted. on the back, of the housing I0 andwhich visadapted forbeing driven through a gear train including the.gears I I4, H6, H8 and pinion I20: by the gear 38. When the bracket I8is in its other operative position, as shown in Figure 9, the. gear 85isspaced from. the pinion H2 and is thus not driven thereby.

Movement of the bracket 1.8 into its Figure 2 position. is accomplishedby a torsion spring I22 connected. between the shaft. 80 and the backwall-of the housing I0. This spring acts through the shaft 80 and arm 23against stop 90 and r0.-

. tates the. bracket. 1.8 counter-clockwise as revealed in Figure 2into. itsv Figure. 2 position.

Thereafter thebracket I8 is moved into its Fig-- ure. 9. position by theengagement-of the arm 88 with the stop 92.

The driving. of the gear train and the bracket 18exerts a thruston thestop 80 which snaps the bracket. into. its. Figure 9 position. notedthat at that time the spring !22 is oper ative. to. drive the gear trainand the arm 83 bat to their starting positions thus to bring aboutmovement of' the bracket I8 back to its Figure 2 position andreengagement of the gear 85 and pinion I I 2.

Mounted aboutthe shaft 80 15a cam plate I24 having a. pin I25 thereinwhich. is adapted for It will beengaging the bifurcated end I28 of onearm of the toggle action switch I30.

tained in frictional driving engagementfwith the shaft 80 by means ofthe disc I34 and the-spring washer I36. The cam plate is furtheradjustable relative to the said disc by means of the screw and slotarrangement I32. v

The operation of the hold-fire portion of the stoker control is asfollows:

Assuming; the bracket I8 to be moyed to its Figure 2 position, the gear88 will be driven and through the pinion 84 and gear 82 will drive theshaft 80 thereby driving the disc I34 and cam plate I24 in a clockwisedirection.

After a predetermined time the pin 128 carried by the cam plate willengage and trip the toggle switch I30 into closed position Thereafterthe-said switch will remain closed during continuous clockwise movementof the cam plate. .Rotation of the cam plate and gearing in the bracketI8 will continue untilijthe arm 88 engages the stop 92. At that time thebracket .18 will be snapped into its Figure :3 position.

88 has moved to the point where it engages the stop 90, it will againshift the bracket I8 into its Figure 2 position and a new cycle-willcommence. r J

It will be apparent that the length of time that the switch I is closedwill be determined by the location of the cam plate I24; relative to thedisc I34 and that the over-all period, including both the closed andopen periods, for the switch I30 will be determined by the spacing ofthe stops 90 and 92.

During normal day time operation of the stoker it is not desired to usethe hold-fire feature and to this end the bracket I04 has a rod I40projecting therefrom which'isadapted for engagement with the plunger I42of a solenoid I44. Energization of the solenoid I44 will move theplunger I42 rightwardly and thrust the bracket I04 in a direction tohold the bracket I8 in its Figure 9 position. I

Theswitches and the solenoid referred to above are connected in circuitwith'a stoker mo tor as shown in Figure 10. In Figure 10 the timingmotor 30 is connected between the power lines ;LI and L2 and in serieswithtan on-off selector switch I48. The-power lineL-I is alsoconnectedgby a wire I48 with the movable contact I2 of the switchingdevice 88.121116 contact I8 of thisswitching device is connected by awire I50 .with one side of a normally 'open thermo'-- static switch I52,the other side of which is connectedby a wire I54 with one terminalv ofthe solenoidi. The other sidejrofthe solenoid I44 is connected by a wireI58 with the power line L2. The other contact I4 Of-1the1SWltChing de-'vice' 88 is connected by a wire I58. with the wire I54 ;and also by awire I60 with-tone side of the thermostatic switch I82, the other sideof which is connected by a wire I84 with one side of a re-' lay-coilI86. The other side'of the relay coil I 68 is connected with thepowerline -L2. The relay is operable? when energized to. .moveits bladeI88 into position to complete a circuit between the lines LI and L2 andthrough the stoker motor indicated at I10. The end of the coil I86connected with the wire I84 is also connected by a wire "2 with one ofthe contacts I32, the other of which is connected by a wire. II4 wit thepower line LI.

The thermostatic switch I52 referred to above is normally open butcloses at a predetermined temperature, whereas the thermostatic switchI82 is normally closed but opens at a predetermined temperature. Theswitch I82 is for the purpose of effecting normal day-time control ofthe stoker motor relay coil I88, whereas the switch !52 becomeseffective for night-time operation and controls the effectiveness of thecycling hold-fire arrangement which includes the toggle switch I 30.

Operation The operation of the stoker control unit of this invention isbriefly as follows:

The stoker motor is connected in circuit with the control unit, thestoker motor, control relay, and the control thermostats as shown inFigure l0.

It will be understood that other suitable and well known thermostaticcontrol elements could be added to the circuit as it is desired, as, forexample, a stack control to prevent the fire bed from overheating, orother elements designed to detect certain temperatures and translatethem into control impulses.

' The unit having been connected in circuit with the stoker motor andthe controlling thermo stats, the pointers 22 are set relative to theirrespective dials I8 and 20 to select the times at which normal day timeoperations of the stoker motor begin and end.

The beginning of the time operation will be determined by the setting ofthe pointer 22 associated with the dial I8, and this pointer and dialarrangement is operative to throw' the switch mechanism at 68 into theposition shown in Figure 10 wherein the contact member I2 closes on thecontact I4.

At this time the thermostatic switch I62 is connected in series with therelay coil I 88, and a circuit is also completed through the solenoidactuator I44 which throws the hold-fire cycling control out ofengagement with the drive motor. Under these conditions the relay coilI88 is energized or tie-energized as determined by the thermostaticswitch I82.

When the temperature of the building being heated by the stokercontrolled furnace reaches a predetermined temperature, the switch I82opens and the relay coil I68 is de-energized and in turn de-energizesthe stokenmotor I10. As mentioned before, the control circuit for therelay coil I88 can include stack controls, low water controls, and othercontrol devices that are well known in the art, if desired.

At th end of a normal day time operating cycle the switch mechanism 88is engaged by the-cam associatedfwith the dial and pointer 20, 22 and isshifted inte position to closethe con tact member I2 on the contact I6.At this time the thermostatic switch I 82 is cut out of the cir-' cuitand loses its control over the relay coil I68. Thec'ircuit through thesolenoid actuator I44 is also interrupted and its control over the holdfire cycling control is also lost. i

As explained before With the solenoid actuator Hide-energized thetorsionspring I22 will shift nuance tme'swlnging :bi-acket I18 intoposition to iibring gears H2 ah'dflBB into engagement. L'Ihis commencesl a timing cycle which will. determine the length of time that thetoggle switch .132 will be closed. This switch is in series-with: therelay coil 1'65 and thus determines vax-period of .energization for thesaid relay coil andtherethrough of theostoker motor H 0. Normally,'thisperiod of: energization offithestoker motor is .ai'matter of .a fewminutes every half hour or houndepending upon. the-average outsidetemperature and the requirements'of "the bu-ilding being heated and, ingeneral, is well known in the stokerfiart.

" Normally, the hold-fire cycling control'will continue to operateunless the temperature of 'thebuildin'gbeing warmed reaches apredetermined am0unt,:at which. time the thermostaticswitch'at I52 willclose and will complete acircuit through the solenoid actuator lt whichwill throw the hold-fire cycling control into inoperativeposition,,th-us permitting the relay 0011- 16B and stoker motor H toremain de-energizedcuntil the building temperature is again reducedto-perm-it the thermostatic switch I52 to open.

Normally, the thermostatic switch-152 is set to open at a lowertemperature than that-at which the switchHiZ willclose, .-and,preferablyboth of the thermostatic' switches are adjustable according towellrknown practices.

.-After a predetermined period of operation under the cycling hold-firecontrol, thecam associated with the pointeriand dial [8, 22 will-againbecome effective to move the switch mechanism- G8.-into its-Figurep0sition,.a-nd the stoken contIG1 :W-i 11 again 'operateon a normal:dayztim'e cycle.

:It will be understood that'this inventionis susceptible to modificationin: orderto adapt it to different usages and conditions and,accordingly, it is desired to comprehend suchrnodificatio'ns within thisinvention as may fall within the scope of the appended claims.

We claim:

'1. In a time switch; a clock Works, a first switch having two operativepositions, cam means driven by said clock works foralternatelyrmovingsaid switch into said positions, a second switch,means for actuating said second switch and adapted for being drivinglyengaged with said 'clockworks, means periodically for engaging anddisengaging said second switch actuating means and said clockworks, andelectrical means energizableior making said last-mentioned meansineffective and connected to said first switch so as tobe energized-whenthe said first switch is'in oneof itsoperative positions.

2. In a time switch having a'clock Works; a first switch, means drivenby said clockworks for alternatel actuating said first switch first.into

one position. and then into another .during --a 1twenty-fourhourperiod'a-second switch adapted for being connectedinparallel with .said first switch, mechanism operable to actuate saidsecond switch according to a predetermined time cycle, means forperiodically engaging said -.,.train "in rsaid bracket adapted "forengagement with said gear upon movement of said bracket in one direction:about its supporting shaft, a torsion spring biasing said gear trainopposite its driven direction, abutment means on said gear train andbracket adapted for engagement in response to the driving of said geartrain a predetermined amount'for moving said bracket out of gearengaging position thereby to release said gear train and to permit saidspring to return it to 'its starting position, said abutment means alsobeing engageable in response to the return of said gear train to itsstartingpositionfor agalnmoving said bracket into its gear engagingposition, and resilient means acting on said bracket to cause it" tomove with snap action between its two uperative positions.

4. In a timing device; a driven gear, a bracket, a shaftrotatably-supporting said bracket, a gear train in said bracket adaptedfor engagement with said gear upon movement of said bracket in onedirection about its supporting shaft, a. torsion spring biasing saidgear train opposite its driven direction, abutment means on said geartrain :and bracket adapted for engagement in response to the driving ofsaid gear train a predetermined amount for moving said bracket out ofgear engaging position thereby to release said gear train and to permitsaid spring to return it to its starting position said abutment meansalso being engageable in response to the return of said gear train toits starting position for again moving said bracket into its gearengaging position, said abutment means comprising spaced stop meanson-said bracket and an arm driven by-said' gear trainan'd movablebetween said members, and resilient means acting on said bracket tocause it to move with snap action between its tw'ooperative positions.

5. In a timing device; a driven gear, a bracket, a shaftrotatably'supporting said bracket, a gear train in said'bracket adaptedfor engagement with said gear upon movement of said bracket in onedirection about its supporting shaft, a torsion spring biasing said geartrain opposite'its driven direction, abutment means on said bracket andgear train engageable in response to the driving of said gear train apredetermined amount for moving said bracket out of gear engagingposition' thereby to release said gear train and to permit said springto return it to its starting position, said abutment means also beingresponsive to the return of said gear train to its starting position foragain moving said bracket into its gear engaging position, said abutmentmeans comprising spaced stop means on said bracket and an arm driven bysaid gear train and movable between said members, means for adjustingthe'angular spacing of said stop mem'- bers' to determine the drivenperiod of said gear train,' and resilient means acting on said bracketto cause it to" move with a snap actionbetween its two operativepositions.

6. In a timing device; a driven gear, a bracket, a' shaft rotatablysupporting said bracket, a gear train in said bracket adapted forengagement with said driven gear in'one position of said bracket andincluding a gear' fixe'dto said shaft, aztorsion spring biasing saidshaftto urge said gear train opposite its driven direction, abutmentmeans comprising spaced abutments on said bracket and an arm on saidshaft for engagement with said abutments for moving said bracket out ofgear engaging position in response toxa predetermined movement thereofwhen driven, said abutment means also being responsive to the return ofsaid gear train under the influence of said torsion spring to itsstarting position for again moving said bracket into a gear engagingposition, a cam on said shaft driven by said gear train, a switchpositioned to be moved into one operative position by said cam duringthe driven period thereof and to be moved into another operativeposition by said cam during the return movement thereof, and resilientmeans acting on said bracket to cause it to move with a snap actionbetween its two operative positions.

7. In a timing device; a driven gear, a bracket, a shaft rotatablysupporting said bracket, a gear train in said bracket adapted forengagement with said driven gear in one position of said bracket andincluding a gear fixed to the shaft, a torsion spring acting on saidshaft and biasing said gear train opposite its driven direction, spacedabutments on said bracket, an arm on said shaft between said abutmentswhereby a predetermined movement of said gear train when driven willmove said bracket out of gear engaging position, and the return of saidgear train under the influence of said torsion spring to its startingposition will again move said bracket into a gear engaging position, acam on said shaft driven by said gear train, and a switch positioned tobe moved into one operative position by said cam during the drivenperiod thereof and to be moved into another operative position by saidcam during the return movement thereof, said cam being adjustablyconnected with said shaft to determine the portion of the driven periodthereof during which said switch will be in each of its operativepositions, and resilient means acting on said bracket to cause it tomove between its operative position with a snap action.

8. In a timing device; a frame, a driven gear, a bracket, a shaftjournalled in said frame and rotatably supporting said bracket, a geartrain in said bracket adapted for engagement with said driven gear inone position of said bracket and including a gear fixed to said shaft, atorsion spring between said frame and shaft biasing said shaft oppositeits driven direction, abutment means on said bracket and shaftengageable in response to a predetermined movement of said shaft whendriven for moving said bracket out of gear engaging position, saidabutment means also being engageable in response to the return of saidshaft under the influence of said torsion spring to its startingposition for again moving said bracket into a gear engaging position,resilient means acting on said bracket to cause it to move with snapaction between its two operative positions, and means selectivelyoperable for retaining said bracket in its gear disengaging position.

9. In a timing device; a frame, a driven gear, a bracket, a shaftjournalled in said frame and rotatably supporting said bracket, a geartrain in said bracket adapted for engagement with said driven gear inone position of said bracket and including a gear fixed to said shaft, atorsion spring between said frame and shaft biasing said shaft oppositeits driven direction, abutment means on said bracket and shaftengageable in response to a predetermined movement of said shaft whendriven for moving said bracket out of gear engaging position, saidabutment means also being engageable in response to the return of saidshaft under the influence of said torsion spring to its startingposition for again moving said bracket into a gear engaging position,resilient means acting on said bracket to cause it to move with snapaction between its two operative positions, and means for retaining saidbracket in its gear disengaging position, said last mentioned meanscomprising a solenoid armature means selectively energizable for movingand retaining said bracket into its gear disengaging position.

HARRY G. MANSON.

ROBERT P. HANSEN.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Number Name Date 1,026,586 Howlin May 14, 19121,440,803 Uphoff Jan. 2, 1923 1,860,159 Porter May 24, 1932 1,885,963Teeple Nov. 1, 1932 2,064,656 Goif Dec. 15, 1936 2,119,187 Teeple May31, 1938 2,163,419 Warren June 20, 1939 2,439,842 Clark Apr. 20, 1948

